Preliminary results of Dickinson, ND study indicate May 20-24 best window for planting in southwest ND

The optimal window for planting sunflower in southwest North Dakota appears to be May 20-24, according to preliminary results of a planting study being conducted by the North Dakota State University Research Extension Center, Dickinson, ND.

Sunflower is considered a late season crop in much of North Dakota, with planting occurring as late as the last half of June. Since southwest ND tends to have less snow cover, soils tend to warm and dry out earlier than in other parts of the state, thus allowing producers to get into the fields sooner in the spring.

Mandan Indians were known to plant sunflower in April in the Bismarck-Mandan area, and sunflower has been planted successfully in late April in parts of Minnesota and South Dakota. Early canopy closure produces a more favorable microclimate of humidity and cooler soils, resulting in a more efficient use of available moisture for plant development. Early canopy closure also provides more competition to late germinating weeds when compared to late seeded crops that shade the ground later in the season. Along with establishing greater yield potential, early seeding should also mean an early harvest, thus providing a greater chance for soils to be recharged with moisture prior to seeding the next crop in the rotation sequence.

Planting early seems better, but what is the optimal sunflower planting period in southwest ND? Roger Ashley, area extension cropping systems specialist in Dickinson, is conducting a study to find out.

The first year of the three-year study was completed in 1999. A mid-season NuSun hybrid (Mycogen 8242NS) was solid seeded on four different dates, beginning April 28, at each of three different locations in southwest North Dakota (Beach, Bowman, Dickinson). Hail, birds, and physiological problems affected the plantings at two of the three locations. At one location where the primary problem was hail, the first date of planting had completed the majority of seed development prior to the hailstorm and yielded more grain and oil than the remaining three dates.

Based on the limited data provided by the first year of this study at Bowman, for each day of delay in seeding between May 23 and June 14 and between June 4 and June 14, there was a 35.2 and 51.8 pound per acre reduction in yield respectively. If sunflower is valued at 10 cents per pound, then the delay between May 23 and June 14 cost $3.52 per acre per day or a total of $77.44 per acre. A delay between June 4 to June 14 would cost the producer $5.18 per acre per day or a total of $51.80 per acre.

In 2000, the study was conducted at the Hettinger Research Extension Center, and on the Miles Hansen Farm, Bowman. Yield differences in 2000 were not as pronounced as in 1999, as it turned out to be a much drier growing season last year than in 1999. Still, delaying planting two weeks from May 24 to June 7 cost $7.23 per acre, Ashley says. Seed oil content, oil yield, and oleic acid content tended to decrease with delayed seeding past the May 23-24 dates in both years, he points out.

Sunflower planted later than May 24 may result in lower yields and oil content, while sunflower planted earlier than May 20 may have greater difficulties with stand establishment because of wireworm, disease, or a combination of cold wet soils and disease, says Ashley. Even with adequate stands, other pest problems such as the sunflower moth can be a problem in early-planted sunflowers in southwest North Dakota, he adds.

More details of the study including an update with data from the 2000 growing season can be found on the Internet, under the link to annual reports, at http://www.ag.ndsu.nodak.edu/dickinso/. – Tracy Sayler

High Plains Planting Timeframe

General recommendations for sunflower planting in South Dakota is mid May to early June, according to Kathleen Grady, South Dakota State University oilseed breeder. “Many wait to plant sunflower until soybeans and corn are planted. That’s not necessarily what we recommend, but that’s what they do. It depend on their crop mix. If sunflower is a main crop, then they give it more attention,” she says.

Oil is generally more affected by late planting than yield, says Grady, pointing to a past study she conducted which indicated that oil content begins to decline in sunflower planted after June 15, and that yield begins to drop in sunflower planted late June. “Although not always. It depends on the year and the environment. But generally, it’s best to plant before June 15 to maximize yield and oil.”

Sunflower can be planted in Kansas from early May to late June, according to the Kansas State University Extension Service. Generally, irrigated sunflower is planted in May and dryland sunflower during the first three weeks of June, according to KSU. Early plantings often result in larger seed size and higher oil, but they encounter more insect problems, and may require treatment. Conversely, late June and early July plantings are prone to smaller seed and lower oil, but fewer insect problems.

Get more planting tips from past issues of The Sunflower archived online at www.sunflowernsa.com. Click on “The Sunflower Magazine,” then “the archives.”